Diffuse illumination10x magnification
With this technique, an open beam is directed on the eye at 45°.This is useful for conducting an overall survey of the eye, lids, lashes, caruncle, sclera, surface vessels and media opacities.

Sclerotic scatter10x magnification.With this technique, a tall, wide beam is directed straight at the limbus. The light is scattered through the cornea to reveal a general pattern of opacities.

Retroillumination
10x-16x magnification.Cataract viewed with retroillumination
Cataract viewed with retroillumination.

Iris retroillumination
Light is reflected anteriorly off of the deeper iris to study corneal opacities and guttata.

Red reflex test
A short light beam is directed through the pupil and reflects off the retina to reveal lens opacities (best with dilated pupil) and iris transillumination (best with undilated pupil).

Optical Section
6x-10x magnification.Radial, midperipheral iris transillumination defects in pigmentary glaucoma.Radial, midperipheral iris transillumination defects in pigmentary glaucoma.A narrow slit beam is angled at 60°onto the limbus to estimate the depth of the peripheral anterior chamber. The angle is considered open if the ratio of aqueous to cornea is greater than 1:2 and narrow when this ratio is no greater than 1:4. Note: This method is not appropriate for plateau iris syndrome.

Conical beam
16x-20x magnification.Using the pupil as a dark background, a bright conical beam of light is angled 45° to 60° onto the aqueous to assess cells and flare. This technique also works with a small rectangular beam.

Corneal cross-section
16x-20x magnification.A thin, bright beam is angled at 45°to 60° for a detailed view of the corneal layers. This technique is used to gauge the depth of lesions and any areas of thinning (ulcers and ectasias).